In the use of light trucks, covers the truck box are often employed. Box covers are useful for protecting the box and cargo from weather, and for protecting the cargo from theft or damage from animals. Some covers are similar to flat lids and are about the height of the top of the truck box. In order to be able to accommodate much higher cargo, some covers have sides, a top, a front, and a back. The box covers to which the invention is directed are non-fabric covers. When using a box cover, certain problems may be encountered. The access to the cargo area is usually through a hinged door at the rear of the box cover. The rear end of the box cover rotates upward and the rear of the truck box rotates downward, creating the access port. Generally it is not possible for a person to enter the cargo area while standing upright. This makes it inconvenient to enter, leave and generally work in the cargo space. It makes it hard to carry objects while stooping. An overhead crane can't usually be employed to handle heavy items. A wheeled dolly is usually not useable because the space available is too low. Even though may canopies have windows which open, it tends to be hot and less well-ventilated within the cargo area than outside it.
Another problem is the limitation on the maximum height of a cargo item. The higher the object which may enter the cargo area, the more useful the truck and cover will be. Many canopies have a lintel which is over the cargo access door at the rear of the canopy. This lintel makes the top stronger but also decreases the height of the access opening. If an object is higher than the available space, the item cannot be transported unless the canopy is removed from the truck beforehand.
Some products have been devised to diminish these problems. One approach is to build a canopy which is higher. If the canopy top is much above the roof of the truck cab, the wind drag of the whole unit is increased. As the height of the canopy is increased above the top of the cab the appearance of the whole unit becomes less attractive. Hence a common approach is to raise only a portion of the roof to a height greater than cab height and to limit this increase to a value deemed to be a balance between more height inside and less attractive appearance and more wind drag. The resulting height, in models seen, does not permit an average person to stand upright inside.
In another approach, the box cover consists of a frame work of metal which is covered with fabric. Parts of the frame slide in tracks along the top of the box. This enables the unit to collapse forward, accordion-style. The result is good access to the cargo area. The styling of the unit is less attractive than units made of rigid material and the theft and animal resistance of fabric is less than that of rigid material.
Another device directed toward the solution of the problem is a roll-out tray for the cargo area. A sturdy tray on rollers covers a large portion of the cargo area. It rolls out of the cargo area, to the rear. Hence a person may access the contents of the tray without stooping and going into the cargo area personally. The tray does not enable the loading of the entire cargo area because of the fenders in the truck box.
While various devices offer certain advantages, it is believed that the invention offers useful advantages over those presently available. An object of the invention is to provide a box cover which provides easy access and enables the operator to stand upright in the cargo area. It is also an object that the box cover allow loading of objects as high as the interior space permits. A further object is to provide a box cover which can easily be adjusted to enable the carrying of objects higher than the normal maximum interior height. A device which can enable present truck canopies to be adapted to accommodate these objectives is an included goal of the invention.